The present invention relates to a system for controlling a clutch for an automatic transmission.
An automobile provided with a continuously variable belt-drive transmission with an electromagnetic clutch is disclosed in EP-A 151038.
In the system, the clutch current characteristic for the start of the vehicle is changed, when idle speed is set at a high value for the use of an air conditioner or idle engine speed is increased (fast idle) by closing the choke valve. Namely, when an accelerator pedal is depressed for starting the vehicle, the engine speed is increased more than the fast idle. If the electromagnetic clutch is engaged in an ordinary manner, the vehicle is jerked, causing shocks. In order to smoothly start the vehicle, the system controls to slowly increase the clutch current so as to gradually engage the clutch.
However, such a system causes other problems. For example, in order to start the vehicle at high speed, when the accelerator pedal is quickly depressed to a wide throttle open position, engine speed may exceed a limit speed, and troubles may occur in the engine and clutch since high engine speed continues for a comparatively long time with slipping the clutch.